Crystals, chiral, absolute

Penzien, K. and G. M. J. Schmidt (1969). Reactions in chiral crystals - an absolute asymmetric synthesis. Angew. Chem. Int. Ed. Engl, 8, 608. 

In this reaction, achiral A-methacryloylthiobenzanilide 39 gave chiral crystals by spontaneous crystallization, and absolute asymmetric synthesis was performed by the solid-state photoreaction leading to optically active thietane-fused 3-thiolactam. The reaction mechanism for the cyclization was elucidated on the basis of the correlation between the absolute structures of both the prochiral starting monothioimide and the photoproduct. 

Even if a molecule is achiral, chiral crystals can form by spontaneous chiral crystallization [26]. The big advantage in utilizing a crystal as a reactant is that absolute asymmetric synthesis can be achieved by solid-state photoreaction of such a chiral crystal. The initial chiral environment in the crystal lattice is retained during the reaction process, owing to the low mobility of molecules in the crystalline state, and leads to an optically active product. The process represents transformation from crystal chirality to molecular chirality. This kind of absolute asymmetric synthesis does not need any external asymmetric source in the entire synthetic procedure [9-14]. 

In 1951, Johannes Martin Bijvoet used such differences in intensity, resulting from anomalous scattering by an atom in a noncentrosymmetric crystal, to determine the chirality (absolute configuration) of the tartrate ion. Details of this method, which has been used extensively for finding the absolute configurations of natural products and for determining macromolecular structures, are given in Chapter 14. 

Glusker, J. P., Carrell, H. L., Job, R., and Bruice, T. C. Mechanism for chiral recognition of a prochiral center, and for amino acid complexation to a Co(III) tetramine. The crystal structure, absolute configuration and circular dichro-ism of A(-)436-/ -[ (25 95)-2,9-diamino-4,7-diazadecanecobalt(III)aminomethyl-malonate] perchlorate monohydrate. J. Amer. Chem. Soc. 96, 5741-5751 (1974). 

Penzien K. and Schmidt G.M. (1969) Reactions in chiral crystals an absolute asymmetric synthesis, Angew. Chem. Int. Ed. Engl. 8, 608-609. Saeva F.D., Sharpe P.E. and Olin G.R. (1975) Asymmetric synthesis in a cholesteric liquid crystal solvent, J. Amer. Chem. Soc. 97, 204-205. Thiemann W. and Teutsch H. (1990) Possible amplification of enantiomeric excess through structural properties of liquid crystals-model for origin of optical activity in the biosphere. Origin ofLife Evolution of Biosphere 20, 121-126 1986,16,420. 

Kawasaki T, Hakoda Y, Mineki H, Suzuki K, Soai K (2010) Generation of absolute controlled crystal chirality by the removal of crystal water from achiral crystal of nucleobase cytosine. J Am Chem Soc 132 2874-2875. doi 10.1021/jal000938... 

This chapter deals with single crystal x-ray diffraction as a tool to study marine natural product structures. A brief introduction to the technique is given, and the structure determination of PbTX-1 (brevetoxin A), the most potent of the neurotoxic shellfish poisons produced by Ptychodiscus brevis in the Gulf of Mexico, is presented as an example. The absolute configuration of the brevetoxins is established via the single crystal x-ray diffraction analysis of a chiral 1,2-dioxolane derivative of PbTX-2 (brevetoxin B). 

Of further particular interest was that the crystallographic results on 2,5-DSP and poly-2,5-DSP had pointed out a very important future possibility that an absolute asymmetric synthesis could be achieved if any prochiral molecule, e.g. an unsymmetrical diolefin derivative, could be crystallized into a chiral crystal and if the reaction of the chiral crystal proceeded in the same manner as the 2,5-DSP crystal with retention of the crystal lattice (Wegner, 1972, 1973). Such types of absolute asymmetric synthesis with a high enantiomeric yield have now been performed by topochemical [2+2] photoreaction of unsymmetric diolefin crystals (Addadi etal., 1982 Hasegawa et al., 1990 Chung et al., 1991a,b). 

Along with the guidepost (Wegner, 1972, 1973) based on the crystal-to-crystal transition from 2,5-DSP to poly-2,5-DSP, absolute asymmetric synthesis has been achieved by the topochemical reaction of a chiral crystal of an achiral diolefin compound in the absence of any external chiral reagents. 

Selenurane oxides are also one of the hypervalent selenium compounds. Recently, the enantiomers of chiral selenurane oxide 38 were isolated for the first time by enantioselective liquid chromatography of the racemate or by spontaneous resolution occurring during slow evaporation of its acetonitrile solution or slow crystallization from the same solvent.57 The absolute configurations of the enantiomers were determined by X-ray crystallographic analysis (Scheme 17). 

Addadi, L., A Link Between Macroscopic Phenomena and Molecular Chirality, Crystals as Probes for the Direct Assignment of Absolute Configuration of Chiral Molecules, 16, 1. 

Crystals as Probes for the Direct Assignment of Absolute Configuration of Chiral Molecules... 

F. Assignment of the Absolute Configuration of a Chiral Crystal Containing a... 

This chapter will be devoted primarily to the assignment of the absolute configuration of a chiral molecule in a crystal by various means. We shall focus mainly on methods that utilize surface structures of crystals, and also examine other avenues that have not yet been experimentally explored but are, in principle, applicable. The review will cover the following topics ... 

The ambiguity involved in assigning the absolute configuration of a chiral molecule in a chiral crystal is presented in Scheme 1. Scheme la depicts a chiral molecule of, say, configuration S, with individual atomic coordinates — x — y - z, (i = 1,. . . , n, for n atoms) in a crystal axial system a,b,c. Scheme 1 b represents the enantiomeric crystal structure containing a molecule of configuration... 

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